Need Help Merging Changes To CM11 Source (Locally)

I am trying to build my own cyanogenmod 11 for my smartphone -> LG G2 (Verizon)
I am able to build from source thanks to many guides. But I need to merge some changes from an author named JackpotClavin on github.

I managed to clone the repo I need locally in dir named 'TESTcm'.

So how do I tell 'brunch' command, that he should use for example

'TESTcm/android_device_lge_vs980' instead of 'device/lge/vs980'
and
'TESTcm/proprietary_vendor_lge' instead of 'vendor/lge/vs980/proprietary' ?

If I use roomservice.xml in local_manifests (and change the corresponding paths), I am not able to repo sync anymore